Visual function detection apparatus, method of detecting visual function, and program

1. A visual function detection apparatus comprising:

a display controller configured to cause an image for determination to be displayed on a display screen of a display unit;

a gazing point detector configured to detect a position of a gazing point of a test subject observing the display screen;

a positional relation detector configured to detect a distance between any position within the image for determination on the display screen and the position of the gazing point; and

a visual function detector configured to perform determination of a trackability of the line of sight of the test subject based on the distance, wherein

the display controller is further configured to move a position of the image for determination in the display screen continuously and change the moving speed of the image for determination,

the positional relation detector is further configured to detect the distance for each moving speed, and

the visual function detector is further configured to perform determination of the trackability of the line of sight of the test subject for each moving speed based on the distance.

2. The visual function detection apparatus according to claim 1 , wherein

the visual function detector is further configured to calculate an average of the detected distance for each moving speed, to determine whether the average is smaller than a tracking threshold set in advance, and to determine that the trackability of the line of sight of the test subject satisfies a trackability criterion for the moving speed if the average is smaller than the tracking threshold.

3. The visual function detection apparatus according to claim 1 , wherein

the display controller is further configured to move the position of the image for determination in the display screen continuously at a second moving speed which is higher than a first moving speed, if the visual function detector determines that the trackability of the line of sight of the test subject satisfies the trackability criterion after performing the examination at the first moving speed.

4. The visual function detection apparatus according to claim 1 , wherein

the display controller is further configured to cause a plurality of types of the images for determination with different contrasts to be displayed at different timings, and

the visual function detector is configured to detect the trackability of the line of sight of the test subject based on the distance for each of the types of the images for determination.

5. A method of detecting a visual function, the method comprising:

performing display control to cause an image for determination to be displayed on a display screen of a display unit;

performing gazing point detection to detect a position of a gazing point of a test subject observing the display screen;

performing positional relation detection to detect a distance between any position within a display region of the image for determination on the display screen and the position of the gazing point;

performing visual function detection to perform determination of a trackability of the line of sight of the test subject based on the distance;

performing movement of a position of the image for determination in the display screen continuously and change of the moving speed of the image for determination at performing display control;

performing detection of the distance for each moving speed at performing positional relation detection; and

performing determination of the trackability of the line of sight of the test subject for each moving speed based on the distance at performing visual function detection.

6. A non-transitory computer-readable storage medium storing a program causing a computer to execute a method, the method comprising:

display control to cause an image for determination to be displayed on a display screen of a display unit;

gazing point detection to detect a position of a gazing point of a test subject observing the display screen;

positional relation detection to detect a distance between any position within a display region of the image for determination on the display screen and the position of the gazing point;

visual function detection to perform determination of a trackability of the line of sight of the test subject based on the distance;

movement of a position of the image for determination in the display screen continuously and change of the moving speed of the image for determination at the display control;

detection of the distance for each moving speed at the positional relation detection; and

determination of the trackability of the line of sight of the test subject for each moving speed based on the distance at the visual function detection.